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The 50cc Eight-Speed Yamaha. 
(Taken from the Motor Cycling December 4th 1966, 
notes provided by Brian Woolley and later amended by JEEP)
Description
The Woolley Yamaha when owned by Ron Ponti
Inception

Brian Woolley of Shepshed, Leics. created this machine in the summer of 1966, aided by Bob Stevenson of Derby and it was the 50cc water-cooled Yamaha special that Trevor Burgess rode and did, in two brief months towards the end of the 1966 racingseason, make a notable mark on its class. It finished second in the Irish Temple 100, setting joint record lap, raising the oldrecord by three and a half miles and hour. It twice won at Cadwell Park and once at Darley Moor and it is the only machine to have beaten Darley specialist George Aston's Honda on its home ground.

Basically a YS-1 engine in a home-made frame, the special was built of readily available parts with an American Gomatic gearbox which gave what is virtually a two-speed back axle to produce 8 ratios. Unfortunately, on Racer Test day at Silverstone, when the machine was put through its paces, this device gave trouble and had to be locked in the high gear, leaving the Woolley - Yamaha very severely handicapped by a shortage of close enough cogs.
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Pictures of the Two Speed Gomatic Gearbox
Balancing the gearing trouble of this Yamaha against the headwind obstruction of Brian Kettle's stock Honda CRII0, Racer tested on September 3rd 1966 (the Honda had a far greater frontal area), the two machines seem to have identical top speeds. Both notched 72.55 mph through the Midland MCRC electronic timer. But the important point is that Woolley's machine costs less to get to the line - and to keep running. It already has a performance to equal that of the CRII0's. And development has hardly begun . . .
Another early trouble was the disintegration of the pressed-paper rotary inlet valve, which always gave up whenever asked to rev to 12,000 r.p.m. This was substituted in favour of a Tufnol disc. At first the 140deg. total-open-period of the inlet valve was extended to 205deg. but Woolley thought that the standard timing was not that far out and he later decided to come back to 195deg. The exhaust top edge was raised to give 170' timing but the three transfer ports were left alone; one port is actuallysplit by a bridge so it could be said there were four transfers.

The dimensions of the exhaust system are not known. "Something that seemed right was welded up; serious exhaust experimentswere to begin before the 1967 season. Opening out the inlet port to accept an 18mm Dell'Orto carburettor completed the basicengine work.

With a narrow power band in prospect, it was realised that the four-speed standard box would be short on ratios. A high-low Gomatic two-speeder was grafted on the rear end giving half a ratio difference.

Minor cir-clip trouble prevented it being used by us at Silverstone. Worked by a grip on the left bar, and needing no clutch or throttle action to change ratio, the American unit theoretically gives eight speeds. In reality, the rider push starts in low and bottom, changing three times on the gearbox to reach top, then shifts into high. Total: five. It is not practical to run through alleight ratios on the trot but the Gomatic's half a ratio is useful on hills to get exactly the right cog.

Triangulated, the backbone type frame was made from mild steel tubes. Suzuki forks were used because Reg Orpin was willing to swap a pair for one of Woolley's hats! The Bianchi and Itom hubs were to hand. Apart from the water-cooling, and the already-mentioned inlet timing alteration, no real tuning had been done prior to the track test day. The weight of the machinefor the test was 120lbs dry with fairing. True development was to start that winter.
Development
Ready for the track at the end of last July, the special was created from a 1964 YS-1 engine and gearbox, a home-brewed frame, Suzuki telescopic forks, a Bianchi front end and an Itom rear wheel.

Devised by Brian Woolley and mostly built by Bob Stevenson, the two-stroke originally had an air-cooled barrel. It was temperamental and unreliable. Brazing on a sheet-steel water jacket around the barrel, with thermo-siphon circulation to a LE Velocette brass radiator, cured both vices. As of the test date, the engine was overcooled. More power was to be forthcoming with the improvement in the water circulation gaining an increase in the jacket temperature. But cylinder-distortion, prime causeof loss of stamina with highly tuned two-strokes, had been eliminated.
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Trevor Burgess on the Woolley Yamaha
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Trevor Burgess at the Temple 100 in Ireland
Preparation
Comments as spoken to the journalist by Brian Woolley

While reliable in a race, the machine is given considerable attention every time we get home. The barrel comes off and the rings are checked. Being very hard, they frequently break but this does not damage the piston or barrel. The exhaust system is scrupulously cleaned out -- that pays real dividends.


After three or four races the crankshaft gas seals are replaced and the Tufnol disc-valve checked for damage and wear. The ignition system gives no trouble and the contact-breaker rarely has to be touched, a novel thing amongst high revving two-strokes. For short events we use a Lodge R5l plug and for long ones the harder R53. Carburetion is remarkably consistent. We nearly always use the same main jet, a 102. Burgess likes his tyres pressured to 26-psi front and 28 rear.
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At the Lexmond Museum 
Riding
(Comments by Bruce Main-Smith)

Added to Owen Greenwood's Mini and Ray Flacks kneeler-Norton, this Yamaha forms the third of a memorial trio in the Racer Test series. It was different and it was fun. There's something appealing about a racing engine which doesn't have or need a rev counter. "Rev it until it goes flat". Those were Woolley's instructions.
Being a 50 and not a 500 it was consequently on full rattle for quite a time and the long bomb down the timing straight together with the very late shut off points were more spells of continuous full throttle.. I kept at it yet the engine never tired,Water-cooling was playing its part.

The little single was vibration-less at any r.p.m. -- whatever they were -- and ever willing. Unlike Kettle's Honda this baby racer was free from drifting, common with to many 50's on corners. It was like riding a bigger bike. Cornering speed were much higher than I realised, or learned in a dozen or so laps to use. Ground clearance was abundant and adhesion at high angles of bank very good indeed.

Mounting the footrests on the un-sprung part of the rear end gave a curious sensation of the feet rising and falling as the restof me stayed still. It didn't spoil my gear changing and I can't help wondering if the increase in un-sprung weight didn't improve handling on bumps for a machine of such extreme lightness. It certainly did not spoil anything because the Yamaha steered impeccably and held the road like glue.

The brakes were entirely adequate and the gear-change light and neat. Push starting could simply be a sit-on-and -paddle job. Just as easy to ride this little special was rev-proof, un-burstable and un-tirable, give it the 12 cogs of a racing Kreidler and it would go places. As it stands it is a pretty cheap, and yet competitive 50.
I found that it sang on and on until the shriek of the exhaust seemed to stop rising. Then I snicked another one in. It was thatsimple. Moreover the engine was very clean down at the bottom-end, whereas some highly tuned two-stroke engines are next doorto impossible. The lack of the extra gears was an undoubted handicap. I held third past the Silverstone pits and after a few laps managed to keep the Yamaha as flat as a kipper round Copse. Top gear went home near the crest before Maggot's left-hander.
Test Data:

*  Track: Silverstone Club circuit 1.608 miles (2.57km). Timing straight 0.6 miles (1 km) with 30-mph approach corner (Becketts)     and 50-mph exit corner (Woodcote)
*  Conditions: Calm winter day. No wind. Temperature from 4°C falling to -1°C. Dry.
*  Track speed equivalent to peak power r.p.m. of 12000: 1st gear=30mph, 2nd gear=50mph, 3rd gear=70mph, 4th gear=95mph.
*  Best speed through trap: Burgess, 72.58. Main-Smith, 69.23.
*  Best flying lap: Burgess, 60.1mph. Main-Smith, 52.00. (Bruce is much taller and heavier than Trevor)
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The Woolley Yamaha at the Lexmond Museum
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The Write-up from the Bonham's Catalogue
1966 Woolley Yamaha 50cc Racing Motorcycle:

Motorcycle engineer Brian Woolley was one of Britain's foremost two-stroke engine specialists and is perhaps best remembered for helping to develop the Greeves Silverstone production racer. The unique machine offered here was created by Brian in collaboration with Bob Stevenson and first raced in 1966 by Trevor Burgess. It is powered by a 1964 Yamaha YS-1 roadster engine modified by the addition of a water-cooling jacket in the interests of reliability. Tuning work consisted of the usual 'port job', fitting an 18mm Dell'Orto carburettor and replacing the rotary inlet valve's compressed paper disc with a Tufnol part giving longer opening. Small capacity engines with relatively narrow power bands are best served by multi-speed gearboxes (Suzuki's 50cc RK67 twin used 14 speeds!) and Woolley ingeniously doubled up the Yamaha's four ratios by using an auxiliary transmission in the form of an American-built 'Gomatic' high/low unit, carried on the swinging arm's left leg.
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Motor Cycling explained the change procedure when its tester Bruce Main-Smith rode the Woolley Yamaha at the end of the 1966 season:  'In reality, the rider starts in low and bottom, changes three times on the gearbox to reach top, then shifts into high. Total five. It is not "practical" to run through all eight ratios on the trot but the Gomatic's half a ratio is useful on hills to get exactly the right cog.' The modified YS-1 engine was installed in a purpose-built spine-type frame equipped with Suzuki front fork, Bianchi front brake and Itom rear hub. 
 
BMS found that the bike 'steered impeccably and held the road like glue. The brakes were entirely adequate and the gear change light and neat.'Completed in the summer of 1966, the Woolley Yamaha with Trevor Burgess aboard had won twice at Cadwell Park, once at Darley Moor and finished second in the Temple 100 in Ireland by the season's end. Motor Cycling estimated the Yamaha's top speed to be the same as that of Honda's CR110 over-the-counter 50cc racer – not bad for a home-built 'special'.

Kept on museum display for the last 15 years, this unique racing '50' is in running condition but will require re-commissioning before returning to the racetrack. The machine is offered with a copy of Motor Cycling's article and a quantity of spares. 

Sold for £7,245 inc. premium
Copyright © Bonhams 2001-2013
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